Analysis of amino acids and organometallic compounds by particle beam–hollow cathode glow discharge atomic emission spectrometry

Abstract

An evaluation of the particle beam–hollow cathode glow discharge atomic emission spectroscopy (PB-HC-AES) system as an element-specific detector for liquid chromatography is described for aromatic amino acids and organomercury and organolead compounds. A high-efficiency thermoconcentric nebulizer is used to introduce analyte particles into a heated hollow cathode glow discharge source for subsequent vaporization, atomization and excitation. Emission responses for hydrogen and nitrogen of amino acids in flow injection mode using 200 µL injection volumes indicate detection limits of 0.13 and 3.6 ppm elemental H and N, respectively, with RSD <10% for triplicate injections over a concentration range of 10−3–10−2 M. Analysis of the response of hydrogen and nitrogen emission signal intensities to differences in amino acid stoichiometries indicates the potential of the PB-HC-AES system for the determination of empirical formulas based on HI/NI intensity ratios. Detection limits for metals and non-metals in organomercury compounds as determined through flow injection of 200 µL sample volumes fall in the sub-ppm range. Liquid chromatographic separations of both amino acids and organolead compounds demonstrate the feasibility of the PB-HC-AES system as a detector for liquid chromatography. Retention times for 20 µL injections of the selected component mixtures as determined by CI emission for amino acids and PbI emission for organolead compounds correlate well with the corresponding UV absorbance results.